Effect of Crystallites on Thermal Shock Resistance of Cordierite Glass‐Ceramics

Thermal shock behavior was compared for a cordierite glass and glass‐ceramics subjected to a water quench. Crystallization significantly increases the critical quenching temperature difference (ΔT c ); this effect was attributed to enhanced strength and thermal conductivity offset by a corresponding increase in Young's modulus. The strength retained following thermal shock also increased significantly on crystallization for ΔT>ΔTC, probably as the result of stepwise increases in fracture toughness with increasing crack size of the glass‐ceramic.